I think the Jem'Hadar would probably LIKE to do some friendly fire, if that would allow them to take out a Vorta in addition to those they see as traitors. But since their "gods" have ordered them to obey the Vorta even when the Vorta are blindingly stupid and arrogant (which they are most of the time)...they can't without going through channels. Which is why Volet'aval wants to skirt around that issue entirely and find an excuse to blow the four Cardassian warships out of space.